Heart failure (HF) is a complex clinical syndrome that can result from any structural or functional cardiac disorder that impairs the ability of the ventricle to fill with or eject blood. The cardinal manifestations of HF are dyspnea and fatigue, which may limit exercise tolerance, and fluid retention, which may lead to pulmonary congestion and peripheral edema. Heart failure is most commonly associated with impaired left ventricle (LV) systolic function. A widely used index for quantifying systolic function is ‘ejection fraction’ (EF), defined as the ratio of stroke volume to end-diastolic volume, which can be estimated using techniques such as radiocontrast, radionuclide angiography, and/or echocardiography. The normal value of EF is 0.67±0.08, which is frequently depressed in systolic heart failure even when the stroke volume is normal. A value of EF≧0.50 is commonly used as an indicator of normal systolic function. It is notable, however, that as much as 30-50% of all patients with typical symptoms of congestive heart failure have a normal or slightly reduced ejection fraction, that is, a value of EF≧0.45.
The term diastolic heart failure (DHF) generally refers to the clinical syndrome of heart failure associated with preserved left ventricular ejection fraction, in the absence of major valvular disease.
Primary diastolic dysfunction is typically observed in patients with hypertension and hypertrophic or restrictive cardiomyopathy, but can also occur in a variety of other clinical disorders and has a particularly high prevalence in the elderly population. Aging is associated with ‘physiologic’ diastolic dysfunction due to the increase in LV muscle mass and changes in passive elastic properties of the myocardium, hence, the concern of an increase in the incidence of diastolic dysfunction as the aging of the western world population progresses.
To one of ordinary skill in the art, there is thus a need for, and it would be highly advantageous to have an in-vivo method and device for improving diastolic function of the left ventricle of the heart, while minimally disturbing systolic function of the heart. Moreover, there is a need for such a method and device which is biocompatible and is specially configured for compact and long-term reliable use in humans.
Various in-vivo methods and devices for improving diastolic function of the heart are described in International patent applications Nos. PCT/IL02/00547, PCT/IL05/01014, PCT/IL04/00986, and PCT/IL04/00072, of the same assignee hereof, the descriptions of which is incorporated herein by reference. The aforementioned international patent applications describe elastic means used for improving diastolic function of the right or left ventricle of the heart by pushing and/or pulling, an inner and/or outer wall region of the ventricle during the cardiac cycle while minimally disturbing the heart function. The present invention provides modifications, improvements, accessories, and new methods and devices, for improving the diastolic function of the heart.
It is an object of the present invention to provide methods and devices for treating systolic and diastolic dysfunctions.
It is a further object of the present invention to provide accessories and a kit for mounting devices for treating systolic and diastolic dysfunctions of the outer surface of the wall of the heart.
It is another object of the present invention to provide improved configurations suitable for mounting ventricular assisting means on the wall of the heart.
Other objects and advantages of the invention will become apparent as the description proceeds.